scholarly journals Optimum Railway Transition Curves—Method of the Assessment and Results

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3995
Author(s):  
Krzysztof Zboinski ◽  
Piotr Woznica
Keyword(s):  
Optimization Methods ◽  
Transition Curve ◽  
Vehicle Model ◽  
Circular Arc ◽  
Passenger Comfort ◽  
Rail Vehicle ◽  
Railway Engineering ◽  
Transition Curves ◽  
Vehicle Movement

This article discusses the optimization of railway transition curves, through the application of polynomials of 9th and 11th degrees. In this work, the authors use a 2-axle rail vehicle model combined with mathematically understood optimization methods. This model is used to simulate rail vehicle movement negotiating both a transition curve and circular arc. Passenger comfort is applied as the criterion to assess which transition is actually is the best one. The 4-axle vehicle was also used to verify the results obtained using the 2-axle vehicle. Our results show that the traditionally used in a railway engineering transition—3rd degree parabola—which is not always the optimum curve. This fact is especially valid for the longest curves, with lengths greater than 150 m. For such cases, the transition curves similar to standard curves of 9th and 11th degrees is the optimum ones. This result is confirmed by the use of the 4-axle vehicle.

scholarly journals Modelling of the shape of railway transition curves from the point of view of passenger comfort

2021 ◽  
Vol 60 (4) ◽  
pp. 205-217
Author(s):  
Krzysztof Zboiński ◽  
Piotr Woźnica ◽  
Yaroslav Bolzhelarskyi
Keyword(s):  
High Speed ◽  
Point Of View ◽  
Transition Curve ◽  
Optimum Shape ◽  
Railway Vehicle ◽  
Vehicle Model ◽  
Circular Arc ◽  
Passenger Comfort ◽  
Rail Vehicle ◽  
Transition Curves

In the past, railway transition curves were not used. Instead of it, a simple connection of the straight track and circular arc was applied. Nowadays, such simplicity is not allowed due to the increasing vehicle operating velocities. It is mainly visible in the high-speed train lines, where long curves are used. The article aims to develop a new shape of railway transition curves for which passenger travel comfort will be as high as possible. Considerations in this paper concern the polynomials of 9th- and 11th-degrees, which were adopted to the mathematical model of the mentioned shape of curves. The study's authors applied a 2-axle rail vehicle model combined with mathematically understood optimisation methods. The advanced vehicle model can better assign the dynamical properties of railway transition curves to freight and passenger vehicles. The mentioned model was adopted to simulate rail vehicle movement in both cases of the shape of transition curves and the shape of circular arc (for comparison of the results). Passenger comfort, described by European Standard EN 12299, was used as the assessment criterion. The work showed that the method using the 2-axle railway vehicle model combined with mathematically understood optimisation works correctly, and the optimisation of the transition curve shape is possible. The current study showed that the 3rd-degree parabola (the shape of the curve traditionally used in railway engineering) is not always the optimum shape. In many cases (especially for the long curves), the optimum shape of curves is between the standard transition curves and the linear curvature of the 3rd-degree parabola. The new shapes of the railway transition curves obtained when the passenger comfort is taken into account result in new railway transition curves shapes. In the authors' opinion, the results presented in the current work are a novelty in optimisation and the properties assessment of railway transition curves.

Railway transition curves and the large circular arc radii

2018 ◽  
Vol 121 ◽  
pp. 423-430
Author(s):  
Piotr Woźnica ◽  
Krzysztof Zboiński
Keyword(s):  
Vehicle Body ◽  
Transition Curve ◽  
Optimum Shape ◽  
Function Evaluation ◽  
Vehicle Model ◽  
Mathematical Methods ◽  
Circular Arc ◽  
Vertical Accelerations ◽  
Optimization And Simulation ◽  
Transition Curves

This work concerns the search for the optimum shape of railway transition curves (TCs). In work the authors used mathematical methods of optimization and simulation. The computer simulation concerned the dynamic behavior of the the 2-axle rail vehicle model. As the transition curve the authors adopted a polynomial of degree n, where n=9 and 11. The quality function (evaluation criterion) used concerned vertical accelerations of the vehicle body. The authors used large circular arc radii – R=3000 m and 4000 m. The aim of the research was to find the optimum shapes of the TCs, taking into account the criterion adopted and comparison of them among themselves.

scholarly journals Exploring Benefits of Using Blending Splines as Transition Curves

2020 ◽  
Vol 10 (12) ◽  
pp. 4226
Author(s):  
Tanita Fossli Brustad ◽  
Rune Dalmo
Keyword(s):  
High Speed ◽  
Transition Curve ◽  
End Points ◽  
Circular Arc ◽  
Track Geometry ◽  
Railway Construction ◽  
Spline Curves ◽  
High Speed Trains ◽  
Transition Curves

Track geometry is a fundamental subject in railway construction. With the demand for increased capacity in terms of load and speed, the need for suitable transitions between consecutive track sections is highly relevant. Properly constructed transition curves lead to improved travel comfort, increased safety, and reduced wear. The well known clothoid curve is widely used as a transition curve; however, the linear curvature is not sufficiently smooth to meet the requirements for railways carrying high speed trains or heavy hauls. Blending spline curves are flexible spline constructions possessing favourable smoothness properties at the end points, which makes them considerable for use as transition curves. This paper demonstrates some selected blending splines applied as transition curves between two existing circular arc segments selected from the Ofotbanen railway. The main results in this paper are related to the smoothness at the end points and the behaviour of the curvature of the curves, where the new transition curves were shown to be smoother than the original clothoid. Another new result is the observation that the proposed method allows for the improvement of existing railways without forcing extensive changes to the original track. Some representative examples are included to highlight the flexibility of this first instance of blending splines as transition curves.

scholarly journals Smoothed transition curve for railways

2019 ◽  
Vol 2019 (7) ◽  
pp. 19-31 ◽  
Author(s):  
Władysław Koc
Keyword(s):  
Final Section ◽  
Initial Section ◽  
Point Of View ◽  
Smooth Transition ◽  
Railway Track ◽  
Transition Curve ◽  
Practical Implementation ◽  
Circular Arc ◽  
New Form ◽  
Transition Curves

The work draws attention to the existing situation in the area of transition curves used in the geometric layouts of the railway track. Difficulties in the practical implementation and maintenance of very small horizontal ordinates of the transition curve and the ordinates of the gradient due to cant in the initial section, appearing on smooth transition curves, were indicated. The main reason for this situation was the excessive smoothing of the curvature in their initial section. Employing the method of curvature identification by differential equations, a new form of the curve was obtained, which was referred to as the "smoothed transition curve". A definite advantage of this curve was shown, from the implementation point of view, over representing the smooth transition curves of the Bloss curve. . It seems that it could successfully compete with the commonly used clothoid, to which it is similar in the initial section, while it differs significantly along its further length, especially in the final section, where it provides a gentle entry from the transition curve into a circular arc.

Optimization of railway transition curves for large circular arc radii

2020 ◽  
Vol 129 ◽  
pp. 73-80
Author(s):  
Piotr Woźnica ◽  
Krzysztof Zboiński
Keyword(s):  
Objective Function ◽  
Body Mass ◽  
Current Paper ◽  
Lateral Acceleration ◽  
Vehicle Body ◽  
Circular Arc ◽  
Rail Vehicle ◽  
Transition Curves

The current paper concerns the optimization of the shape of railway transition curves (TCs). As transition curves, the authors used the polynomials of 9th and 11th degree. In the optimization of the shape of the TCs, the model of 2-axle rail vehicle was used. The mentioned objective function concerned the normalised value of the integral of the change of lateral acceleration of vehicle body along the route. The authors used large circular arc radii – R=3000 m and 4000 m. The paper presents the results of the optimization - the types of curvatures of the optimum transition curves and the dynamical courses - the displacements and the accelerations both lateral and vertical of the vehicle body mass centres.

scholarly journals Optimization of Polynomial Transition Curves from the Viewpoint of Jerk Value

2017 ◽  
Vol 63 (1) ◽  
pp. 181-199 ◽  
Author(s):  
K. Zboinski ◽  
P. Woznica
Keyword(s):  
Optimization Procedure ◽  
Optimization Methods ◽  
Simulation Software ◽  
Vehicle Model ◽  
Vehicle Simulation ◽  
Numerical Tests ◽  
Full Vehicle ◽  
Freight Car ◽  
Transition Curves ◽  
New Criteria

Abstract The aim of the presented paper is to show the results of shape optimization of railway polynomial transition curves (TCs) of 5th, 7th, and 9th degrees through the use of the full vehicle model and new criteria of assessement concerning the jerk value. The search for the proper shape of TCs means that in this work, the evaluation of TC properties is based on select quantities and the generation of such a shape through the use of mathematically understood optimization methods. The studies presented have got a character of the numerical tests. For this work, advanced vehicle models describing dynamical track-vehicle and vehicle-passenger interactions as well as optimization methods were exploited. In the software vehicle model of a 2-axle freight car, the track discrete model, non-linear descriptions of wheel-rail contact are applied. This part of the software, the vehicle simulation software, is combined with a library optimization procedure into the final computer program.

Design of backlash-free straight-curved guide devices

2014 ◽  
Vol 228 (15) ◽  
pp. 2833-2843
Author(s):  
Long-Iong Wu ◽  
Kuan-Lwun Shu
Keyword(s):  
Common Point ◽  
Transition Curve ◽  
Circular Arc ◽  
Contact Points ◽  
Straight Line ◽  
Pitch Curve ◽  
Slider Motion ◽  
Guide Device

This article presents a method for designing a planar guide device that can guide sliders to move along a straight-curved rail and can eliminate the backlash between the slider and the rail throughout the whole range of the slider travel. The guide device has many sliders and each slider has three rollers that can separately roll on both sides of the rail. The straight-curved rail is composed of straight sections, connection sections, and circular-arc sections. For each slider, the three normal lines through the contact points between the rollers and the rail must always intersect at a common point, which is an instant center. Using this as a basis, the side profiles of the straight-curved rail can be determined. To avoid infinite jerk of the slider motion, the pitch curve of the connection section should consist of a transition curve, which is interposed between the straight line and the circular arc.

On the Planning and Construction of Railway Curved Track

2021 ◽  
Vol 13 (2) ◽  
Author(s):  
Sono Bhardawaj ◽  
Rakesh Chandmal Sharma ◽  
Sunil Kumar Sharma ◽  
Neeraj Sharma
Keyword(s):  
High Speed ◽  
Time Derivative ◽  
Railway Track ◽  
Lateral Acceleration ◽  
Transition Curve ◽  
Railway Vehicle ◽  
Geometric Conditions ◽  
Curve Track ◽  
Curved Track ◽  
Transition Curves

Increasing demand for railway vehicle speed has pushed the railway track designers to develop high-quality track. An important measure of track quality is the character of the transition curve track connecting different intersecting straight tracks. A good transition curve track must be able to negotiate the intermittent stresses and dynamic effects caused by changes in lateral acceleration at high speed. This paper presents the constructional methods for planning transition curves considering the dynamics of movement. These methods consider the non-compensated lateral acceleration, deviation in lateral acceleration and its higher time derivatives. This paper discusses the laying methods of circular, vertical and transition curves. Key aspects in laying a curved track e.g. widening of gauge on curves are discussed in this paper. This paper also suggests a transition curve which is effective not only from a dynamic point of view considering lateral acceleration and its higher time derivative but also consider the geometric conditions along with the required deflection angle.

Development of a reduced dynamic model for comfort evaluation of rail vehicle systems

2016 ◽  
Vol 230 (4) ◽  
pp. 489-504 ◽  
Author(s):  
Mortadha Graa ◽  
Mohamed Nejlaoui ◽  
Ajmi Houidi ◽  
Zouhaier Affi ◽  
Lotfi Romdhane
Keyword(s):  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Dynamic Models ◽  
Railway Vehicle ◽  
Passenger Comfort ◽  
Rail Vehicle ◽  
Vehicle System ◽  
Comfort Evaluation ◽  
Complex Models ◽  
Reduced Dynamic

In this paper, an analytical reduced dynamic model of a rail vehicle system is developed. This model considers only 38 degrees of freedom of the rail vehicle system. This reduced model can predict the dynamic behaviour of the rail vehicle while being simpler than existing dynamic models. The developed model is validated using experimental results found in the bibliography and its results are compared with existing more complex models from the literature. The developed model is used for the passenger comfort evaluation, which is based on the value of the weighted root mean square acceleration according to the ISO 2631 standard. Several parameters of the system, i.e., passenger position, loading of the railway vehicle and its speed, and their effect on the passenger comfort are investigated. It was shown that the level of comfort is mostly affected by the speed of the railway vehicle and the position of the seat. The load, however, did not have a significant effect on the level of comfort of the passenger.

scholarly journals Mesomorphism Dependence on Cis-Trans Configuration and Varying Terminal/Lateral Group

2016 ◽  
Vol 65 ◽  
pp. 71-79
Author(s):  
G.N. Bhola ◽  
Umed C. Bhoya
Keyword(s):  
Thermal Stability ◽  
Homologous Series ◽  
Vinyl Ester ◽  
Molecular Structures ◽  
Transition Curve ◽  
Group Efficiency ◽  
Lateral Group ◽  
Normal Manner ◽  
Thermotropic Liquid Crystals ◽  
Transition Curves

A chalconyl trans vinyl ester homologous series of thermotropic liquid crystals RO-C6H4-CH=CH-COO-C6H4-CH=CH-CO-C6H3(OCH3)2meta-para is synthesized and studied with a view to understand and establish the relation between molecular structure and mesomorphism or mesomorphic behaviors. Novel homologous series consists of thirteen homologues (C1to C18). First five (C1to C5) homologues are nonmesogenic. Rest of the homologues (C6to C18) homologues is mesogenic. Monotropically smectogenic character appears from C6to C10homologue and C12to C18homologues are enantiotropically smectogenic. Nematogenic property is totally absent throughout a series. Textures of smectic phase are of the type smectic A or C. Transition curves of a phase diagram behaved in normal manner. Analytical, spectral and thermal data supports the molecular structures of homologues. Odd-even effect is observed for Sm-I/I-Sm transition curve. Thermal stability for smectic is 93.7 °C and the mesomorphic phase lengths from enantiotropic homologues for smectic from minimum to maximum is 6.0 °C to 28.0 °C at the C12and C18homologue respectively. Series is smectogenic without exhibition of nematic property. The group efficiency order on the basis of thermal stability is derived; from comparative study of present series and analogous series.

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